User consent and third-party clients

The OIDC-conformant authentication pipeline supports defining resource servers (i.e. APIs) as entities separate from clients. This lets you decouple APIs from the applications that consume them, and also lets you define third-party clients that you might not control or even fully trust.

Types of clients

All Auth0 clients are either first-party or third-party.

First-party clients are those controlled by the same organization or person that owns the Auth0 domain. For example, suppose you wanted to access the Contoso API; in this case, there would likely be a first-party client used for logging in at contoso.com.

Third-party clients are controlled by different people or organizations who most likely should not have administrative access to your Auth0 domain. They enable external parties or partners to access protected resources at your API in a secure way. A practical application of third-party clients is the creation of "developer centers", which allow users to obtain credentials in order to integrate their applications with your API. Similar functionality is provided by well-known APIs such as Facebook, Twitter, GitHub, and many others.

Creating a third-party client

All clients created from the management dashboard are assumed to be first-party by default.

At the time of writing, third-party clients cannot be created from the management dashboard. They must be created through the management API, by setting is_first_party: false.

All clients created through Dynamic Client Registration will be third-party.

If a user is authenticating through a third-party client and is requesting authorization to access the user's information or perform some action at an API on their behalf, they will see a consent dialog. For example:

GET /authorize?
client_id=some_third_party_client
&redirect_uri=https://fabrikam.com/contoso_social
&response_type=token id_token
&scope=openid profile email read:posts write:posts
&audience=https://social.contoso.com
&nonce=...
&state=...
Auth0 consent dialog - Fabrikam Client for Contoso is requesting access to your account

If the user chooses to allow the application, this will create a user grant which represents this user's consent to this combination of client, resource server and scopes. The client application will then receive a successful authentication response from Auth0 as usual.

Handling rejected permissions

If a user decides to reject consent to the application, they will be redirected to the redirect_uri specified in the request with an access_denied error:

HTTP/1.1 302 Found
Location: https://fabrikam.com/contoso_social#
    error=access_denied
    &state=...

Only first-party clients can skip the consent dialog, assuming the resource server they are trying to access on behalf of the user has the "Allow Skipping User Consent" option enabled.

Consent can't be skipped on localhost

Note that this option only allows verifiable first-party clients to skip consent at the moment. As localhost is never a verifiable first-party (because any malicious application may run on localhost for a user), Auth0 will always display the consent dialog for clients running on localhost regardless of whether they are marked as first-party clients. During development, you can work around this by modifying your /etc/hosts file (which is supported on Windows as well as Unix-based OS's) to add an entry such as the following:

127.0.0.1       myapp.local

Once you do this, remember to update your client configuration URLs (such as Allowed Callback URLs) to match the updated domain-mapping!

Since third-party clients are assumed to be untrusted, they are not able to skip consent dialogs.

Password-based flows

When performing a Resource Owner Password Credentials exchange, there is no consent dialog involved. During a password exchange, the user provides their password to the client directly, which is equivalent to granting the client full access to the user's account.

When redirecting to /authorize, the prompt=consent parameter will force users to provide consent, even if they have an existing user grant for that client and requested scopes.

As of today the consent dialog UI cannot be customized or set to a custom domain. We plan to implement this in future releases.